Plaster applicator



March 10, 1953 P. H. SOMMERS PLASTER APPLICATOR 4 Sheets-Sheet 1 Filed May 25, 1949 INVENTOR. Edd ff 'ommefifi aw J March 10, 1953 P. H. soMMERs 2,630,703

PLYASTER APPLICATDR Filed May 25. 1949 4 she'ets -sheet 2 INVENTOR. Zaul H Sam-mews March 10, 1953 P. H. SOMMERS 2,630,703

PLASTER APPLICATOR Filed May 25. 1949 4 Sheets-Sheet 3 INVENTOR. Paafi 50%1726/25 BY 4 f a I l March 10, 1953 P, H. SOM'MERS 2,630,703

PLASTER APPLICATOR Filed May 25. 1949 4' Sheets-Sheet 4 Patented Mar. 10, 1 953 UNITED STATES PTENT OFFICE 1 Claim.

The present invention relates to the art of lastering, and is concerned with the provision of a mechanical aid to facilitate the application of a coating or layer of plaster to a wall. When I speak of plaster herein, I do not use the term in a restrictive sense, but intend to include such plastic self-setting materials as stucco, mortars, cements, and the like. The device may be employed for applying plastic material which is not self -setting, but in the building trades self -setting plastics are the usual ones employed. The term mortar is used interchangeably with plaster except as the context indicates otherwise. I use the term wall to designate a supporting surface in any position, and of any usual contour that may be encountered in the building trades.

The spreading of a mass of plastic material, such as plaster, upon a surface, such as the wall of a building, calls for considerable skill, and involves a good many motions.

After a batch of plaster is prepared, a limited supply thereof is transferred to a hawk held in one hand of the artisan, which hawk serves as a support for said limited supply of plaster, and as a means for feeding small amounts of said supply to a trowel in the other hand of the workman. The trowel with its burden is then applied to the surface to be coated, and the charge or burden carried by the trowel is simultaneously spread out into a film'and pressed against the supporting surface to secure adhesion which may involve partial penetration of the supporting wall, particularly where lath,

plasterboard, expanded metal and the like are employed to support the plaster. Then the trowel is applied to smooth the surface and to some degree to equalize the thickness of the film over the area covered.

To convert a lump or mass of relatively soft plaster into a film is not per se a diflicult matter. Children do that in making mudpies. But to cover an area with a reasonably uniform film by repeated applications of masses or lumps and trowelling them out into a continuous film, particularly upon a foraminous support such as lath, expanded metal or the like, gives opportunity for error at each application of an additional mass or lump. To smooth out the result of applying each mass or lump similarly gives opportunity for error as it may result in excessive penetration of the foraminated support and too thin a coating on the exposed surface, or it may result in too great thinning out laterally of the plaster applied. It is in successfully by-passing these opportunities for error that the skill of the artisan reveals itself.

In addition to the above requirements for skill, the operations of repeatedly adding small increments and flattening them into a continuous film or layer appears to me to involve a large number of motions which could be avoided by some more general action or motion which would combine the efiects of a great many of them.

It occurred to me that it might be possible to develop a mechanical device which would, in its structure and mode of operation, avoid or eliminate some of the opportunities for error now calling for the exercise of skill and judg ment. By building the skill into the machine as it were, I would remove the need for at least a substantial part of the skilled operations required by present practice by substituting the simpler manipulation of the machine itself.

I conceived that the intermittent operation of applying and trowelling small increments might be combined into an action characterized by continuity. I conceived that the critical problem of gauging the uniformity of film depth might be combined with the continuous feeding and trowelling, and that a relatively large amount of plaster could be thus handled and applied all at one operation.

I am aware that magazine tools and devices for continuous feeding of a plastic material are old, but, so far as I am informed, no satisfactory device of general utility in the art of plastering has been evolved. This is, I believe, chiefly because no device has actually performed the interrelated functions of continuously supplying the plaster, feeding it out through a metering open-- ing, gauging the proper depth of layer deposited, and trowelling the layer to secure the desired penetration at the inner surface and smoothness on the outer surface, which my device performs.

A further object of my invention is to provide a device which, while relieving the operator of the necessityfor exercising skill, will itself be of simple construction, low cost, and inherently simple to operate for the various functions to be performed by it.

In the preferred form of my invention, I proviole the combination of a mortar storage chamher or magazine, a regulating depth guide and a screed with trowelling action to apply a uniform layer of mortar on any surface to which the material is to be applied. Rapid loading of the chamber is possible by simply reversing the position of the device and scooping up a supply. The need for the hawk and trowel for the application of plaster, stucco, mortar and, the like, in all planes, is eliminated by the device of my lieves him of the necessity for exercise of judg-, ment, and in either case permits of the attaine ment of a vastly greater output for the same ill amount of exertion or within a given period of time.

Now in order to acquaint those skilled in the art with the manner of constructing and operatdrawings, a preferred embodiment of the invention and its structure and mode of use.

In the drawings:

Figure l 'is an isometric view of an embodiment "of my invention'heldiin' the position'in which it" I is'used in applying plaster to a vertical'wall;

ing a device embodying my inventiori','I"shall de scribed, in connection with the accompanying Figure 21s a similar isometric view of a form 'of'applicat'or for applying'plaster 'to a ceiling or other horizontal wall, as well as to a vertical wall;

Figure 3 is a diagram illustrating the method of" charging the magazine when the device is in loading position.

Figure 4 is a similar diagram showing the device offFigu're 1 in a carrying positionwhen it is loaded.

V Figure 5 is a diagram of the device of Figure 1,"

" illustrating the method of placing the applicator in position to apply'plaster to a vertical wall; Figure '6 is a similar diagram showing the device applying mortar to the vertical wall;

7 Y Figures 7 to are diagrams-of the mode of use ofthe device of Figure 2 Figure 7 shows the device of Figure 2 being I loaded with mortar or'plaster;

strap" I3 mounted preferably at the botto'morfeedingplate 9.

Figure 8 shows the deviceloaded and then bein'g disposed in carryin'gposition;

- Figure 9 's'hows'the device as being brought into *position to apply plaster to a horizontal wall; 7

Figure 10 shows the operation of applying plaster to the ceiling or otherh'orizontal wall; and

Figure 11 is an isometric View, similar to Fig-' ure 1, showing the disposal of a mechanical or electrical vibrator unit on the magazine'to. assist in handling-stiff mortars or plastic materials, and

trowelling the same upon a wall.

Like reference characters indicate like parts throughout.

The device shown in Figure 1 comprises essen-' tially a magazine portion I, runners 2, z which' form depth gauges for the layer to be applied, a throat plate 3, whichforms with the runners 2 a mated)" The throat plate 3 is preferably set at a slight angle to the plane determined by the 'edges or the runners 2, 2, so that the resulting throat is tapered and tends to exert pressure of the sheet or plastic against the'wall to which it is applied. The handles comprise a handle 5 I for supporting the magazine 'end ofth device, I

and a handlefi for supporting the trowelling end throat or screed to measure out and squeeze against the surface a sheet of the plasticbeing lappliedfa flexibletrowelling'margin or edge 4 for trowelling the layer of plastic deposited,and han-' ed adjustably by screws i7 threaded into the 4 with the open end truncated or cut on a diagonal plane which may be approximately 45 to the longitudinal axis of the box. As shown in Figure l, the end closure wall I which becomes the bottom wall when the device is carried loaded, as shown in Figure 4, is joined to the top or loading wall 8, and the bottom or outlet wall 9 and the two side walls Hi, It, which latter are alike in size and ,outline. The loading wall 8, which is normally uppermost when the device is used for applying plaster to the wall, is shorter than the outlet wall 9 which is lowermost when the device is in position for applying plaster to a wall. The

wells of the device are preferably formed. of sheet metal, being generally rectangular in outline, and of appropriate dimensions. In an embodiment .which. I have successfully operated, the loading wall is approximately 8 inches from the loading edge to the end closure, and approximately 12 inches in width along the loading edge. The

' feeding'wall 9 is of the same widthas the loading wall and is of greater length, namely, approximately 12 inches. The throat plate is of approximately three inches in length along the line of 'flowof the material, and the trowelling plate extends approximately 1% inches beyond thethroat line andterminates in a free flexible edge. The

' steel sheet approximately 0 thick.

These dimensions are'given by way of exemplification and not of limitation] The handle 5 at the rear of the device is connected to twoupright posts I2, I2 which are'welded toa reinforcing the rear edge of Figure l; by the crossbar l5 of angular cross section. Posts lb, lfi securedito the angle bar l5, welding, "suppo t the hand grip 6 at .the trowelling end of the" deviel The side edges'of the sheet metal throat plate 3 may be bent up "at right angles to the plane l of the plate 3, "and clamped; between the" runners 2 and the s'ide'bars M for supporting rigidly the of the throat plate 3 may likewisebe'bentup at right angles", and folded flat against fthe lower leg of the angle bar [Band secured thereto to reeriforc the iorward edge of the throat'fplate.

The trowelling'plate, of which free flexible edge acts tohforma smooth surface or the coating, is secured to' the inside'face of the" throat plate 3'by suitable screws or rivets,- preferably leaving a flush surface for'eas e in travel over the s'urfa'ceof the'layefofplaster.

The depthgaugesfor runners 2, Zare mountside times" l4, l4 and extending ti irough slots "dle's'by Ineansof which thedevice may be manip- 18,18, whereby the runners '2, 2 "may be adjusted 1forcontrolling" the depth of layer a'ppliedto the wall or surface."

The mode of use of the device of l3figure 1 is illustrated'inFigures' 3, 4, 5 'and"6.'

The'loadingof the devicefis illustrated in Figure pilebfmortar of plaster is 'dieposited on a supportingisurface 'fli which In I b e either a mortar board or the rnor'tar' box or the like. The deviceis graspedby ftheharidsfi and E with the loading wall tldispos'ed substantially fl ?[these re iiihal r ia e 29; a O

end of the deviceis shoved suitable surface, such as lath, expanded metal, screen, plasterboard, tile or the like, which is customarily subject to the application of plaster.

In modern practice, the plaster is generally applied to metal lath or to plaster board. Plaster board is supplied in two common forms; one form consists of plain gypsum board covered with a layer of absorbent paper and provided with rounded edges. The other form consists of gypsum board covered with an absorbent paper and having a pattern ofholes of approximately one inch in diameter punched through the body. In either structure, adhesion of the plaster to the board is secured through the absorbent paper. In the first example, bond and adhesion are assisted by forcing the plaster into the openings and recesses formed at the junctions of the edges and at the rounded corners. In the second example, the extrusion of the plaster through the openings locks the plaster to the board.

Figure shows the device being raised into position by applying the trowel 4 at the point where the previous application has deposited the layer of plaster 22, and the device is swung up-- wardly in the direction of the arrow into the dotted line position where the runners bear fully and evenly upon the supporting surface. The device is then stroked upwardly as shown in Figure 6. The mortar flows down the outlet wall 5 between the throat plate 3 and the wall, and is finally engaged by the flexible trowel portion 3, which smooths and presses to a uniform depth the layer of mortar applied.

The throat defined by throat plate 3, the side runners 2, 2 and the wall surface 2i is preferably tapered at a low angle to develop pressure of the plaster against the surface of the wall as the material flows out of the reservoir and spreads on the wall. The angle of this plate relative to the wall may be adjusted to secure greater or less wedging action upon the plastic. The operator may apply greater or less pressure upon the flexible trowel plate 4 by rocking the entire device about the forward ends of the depth guide runners 2-2 while the said runners are in engagement with the wall surface being operated upon. Cement mortars are rather low in plasticity, as compared to lime mortars or plasterers, which characteristic makes them more difficult to apply, particularly to a vertical wall or to a ceiling. Hence, considerable pressure is desirable to press the material against the wall for attaining maximum density and to secure the desired adhesion and bonding. The taper of the throat assists in developing the desired pressure. Sufficient adjustment of the angle of the throat relative to the wall may generally be made merely by tilting the runners 2, 2 on the frame, since the flexible troweling plate will accommodate itself to the same by its flexibility.

The longitudinal axis of the device is at approximately l5 to the vertical wall 2! in the application of the mortar to the wall. The mortar usually is sufliciently free flowing that it will gravitate readily into the confined space between the guide runners and the throat plate,

The wall 21, shown in Figure 5, to which i a layer of plaster is to be applied, may be any v pass through the tapered throat and be engaged by the trowel portion 4. If particularly stiff mortar is used, then a mechanical or electrical vibrator 23 attached to the bottom wall 9, as shown in Figure 11, may be employed. The device of Figure 11 with the electrical vibrator 23 is otherwise substantially identical with the device shown in Figure 1. Such a vibrator is.

well known. It consists of a rotating shaft with.

an eccentrically carried weight. Other means for developing a vibration or shaking action may be used.

The guides or runners 2, 2 may be adjusted. for depth of layer, as previously explained, and

. they may be adjusted to apply a skim coating, asv

fer finishing the surface of rough plaster.-

The device of Figure 2, which is designed for application of plaster to a horizontal wall, such. as a ceiling, differs from the device shown in Figure 1 in having provision for a movable end closure for the magazine I by which the mortar may be expelled therefrom. Otherwise it is like the device of Figure 1.

In the use of the device of Figure 2, the magazine will extend diagonally downwardly at a 45 angle to the ceiling, and it is necessary that the mortar be raised into the throat to secure the deposit of the desired layer. The outer margins or ends of the walls 8, 9, I0, I11, which form the boxlike magazine, are supported by an angle iron frame 25 for stifiening the end of the box maga zine, and for forming a support and guide for the rods 28, 26 upon which the piston or plunger 27 in the box is carried. The piston 21 is rectangular in outline, and fits closely inside of the box, so that it acts as a movable wall for expelling the mortar in the magazine. The rods 26, 26- are guided in tubular guides 28, 28, which in turn are supported in cross bars 29, 29, attached to the angle iron frame 25. The two rods or plungers 26, 26 are joined at their outer ends by a hand grip 36 for operating the piston 21. The mode of use of the device of Figure 2 is illustrated in the diagrams of Figures '7 to 10.

To prepare the device for loading, the handle 3i! is pulled outwardly, so as to bring the piston 27 to its outward position. Thereupon the device is laid flat on the loading surface 20 as shown in Figure 3. A charge of mortar is scooped up by moving the device, as illustrated in Figure 7, and the device is upended as illustrated in Figure 8 to carry the same to the point of use. Then, as shown in Figure 9, the flexible trowelling edge 4 is applied to the margin of the previous layer of mortar 32. The device is swung upwardly to bring the runners into engagement with the surface 3l, as shown in the dotted line position in Figure 9. Thereupon, as shown in Figure 10, pressure is applied to the handle 30 to expel the mortar into the throat as the discharge end of the device is held up with the runners against the ceiling surface by means of the handle 6.

With the two hands the device is then stroked towards the left as viewed in Figure 10, discharging mortar and trowelling the surface thereof in substantially the same manner as illustrated previously in Figure 6.

From the foregoing it will be apparent that my invention provides a simple, inexpensive mechanical aid for permitting the rapid and satisfactory application of mortar to a wall surface by one lacking the skill of the artisan. Alternatively, a skilled artisan with the use of my device may greatly increase his output and lessen the effort of the work. The device facilitates the continu- 'feeding ofma,.plastic:z-materialuthrough the".

' metering throat definedby the throat p1atei3 and the guides/orvzrunners 2;;2, and: the wallsurface; The depth of. the layerwisdproperly.v gauged, a uniform pressure is irapplied', and. thewsurface is": trowelled smooth; all in a simple-movement, skillv in vthe performance; of which may I be acquired in short order. v-further vadvantage: is the I 7.

Variations of the specific structure will'be made by those; skilledin: 1311812113, and lxdofnot intend to vbe limited to. the detailszshown 'ordescribed except-as'theyzare made essential byjthe appended claim.

I claim: In a device of the class describedyatsubstantially rectangular boxlike magazinefor =plaster open at one end only, 'said'magazine comprising an outlet wall and aloading wall, said walls being substantially parallel to each" other, th'e 'outlet wall being longer than the loading wall; and the" edges of said-twowalls' at-the openend of the side- Walls:substantiallyi'parallel to each"- other and-joining the loading walland" the outlet wall,

5 saidextensions!constitutingzdepth guides or runners for determining thedepth ofsplasterto be deposited, and a fiat flexible troweling plate having its rear edge connected to the outlet wall at said open end of "the magazine and extending forwardly beyond said parallelrunners and being :free at its frontandside edges to bear yieldingly .upon the plaster which issues from .the open end of the magazinebetween said depth guides, said trowelling plate. lying in aorplane substantially parallelto the first saidplane.

7. 4 PAUL H. a SOMMERS.

.. I J REFERENCES" CITED The :following references are: o record in the 2651119. 01111131 patent:

UNITED STATES "PATENTS Number I Name Date Y 482,369 H Kruck Sept. 13, 1892 5 r 807,301. Montanlnnlhnn Dec. 12, 1905 v $845,530 'Feb. 26, 1907 1,828,738 Oct. 27', 1931 ..2,098,8'70 .--HeltzeL-nheaahn-n Nov. "9, 1937 

